In automatic focusing (AF type) cameras, generally, the distance to a subject to be photographed is measured by triangulation.
In this method, an infrared beam is projected from a light projecting element toward the subject, the reflected light from the subject is received by a light receiving element, and the distance to the subject is calculated on the basis of the point of the light receiving element that receives light.
In such a method, wherein only one light projecting element is used, however, it is difficult to obtain a correct distance unless a subject to be photographed is positioned at the center of a finder. In view of such circumstances, a so-called multi automatic focusing (multi AF type) range meter is also known (see, for example, Japanese Patent Laid-Open No. 87-223734) which uses a plurality of light projecting elements. In this multi AF type range meter, a plurality of light projecting elements are arranged in a row, and they project their beams of light in different directions. The light projecting elements are controlled such that they emit light at different emission timing in time-division manner.
The irradiation beam projected from each light projecting element toward a subject to be photographed weakens as the distance to the subject increases, and thus is simply influenced by noise or variation. Therefore, conventionally, to remove the influence of noise or variation, each light projecting element is caused to emit light several times and a set of range data thus obtained is averaged. Accordingly, a conventional multi AF type range meter consumes much power.